I'm building a multi-stage coilgun for a science fair project, and am about to add a third stage to it and was wondering if spin could be applied to the projectile without rifleing or modifying the projectile, thats when I came up with this:
http://i790.photobucket.com/albums/yy186/grunt009/Picture001.jpgBut I dont know if the discharge time would be long enough for the rotation to effect the projectile, or if rotating the coil could even make the projectile rotate. I'm also having trouble finding information rotating magnetic fields. If it does work however, I may need to slot the projectile as rotation in the magnetic field could generate eddy currents and slow or reverse the projectile. Any thoughts, suggestions, or random ramblings? Once again, any help is appreciated.

just an idea i cant say it will work but, if when you load the projectile and took care to make sure to load it exactly the same way every time, you could place small permanent magnets on the projectile then place permanent magnets at different places on the barrel and lined them up so that like charges repel in the direction you want it to spin.

here is a very poorly drawn picture
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I cant be sure, as i am not positive about my magnetic knowledge, but im not sure it would add spin as the nail is not North/South discriminant. By this, i mean it is not magnetized, but it is still magnetic (it will stick to a magnet) In order for your idea to work, i believe you would need a nail that was North on one side and south on the other, and have your rotating coil also be North/South.

Again, i cannot be held responsible for the information contained in my post

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rag, are you saying that the permanent magnets on the projectile will interfere with the accelerator coils? if not why would it not cause it to spin as it is moving forward? the acceleration coils should be exerting a much larger force than the magnets to produce spin.

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A second thought I'm not sure of but the following is common electrical knowledge.

Grab yourself an AC motor, yoink out the rotor, drop a steel ball bearing in and switch the motor back on.

The ball bearing will start spinning round the inside of the motor. The coils in the motor are turning on and off in sequence, creating a rotating magnetic field. In normal use the squirrel cage rotor inside the AC motor has torque put on it by the rotating magnetic field causing it to spin.

You'd have to (a) have a very specially made projectile (b) use alternating current and (c) probably lose sight of the barrel under all the coils.

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Last edited by Hotwired on Wed Aug 19, 2009 4:52 pm, edited 1 time in total.